This invention relates generally to agricultural balers of the type commonly referred to as square balers that produce bales having a rectangular cross section, and more particularly to an improved plunger guide apparatus that increases stability of plunger movement in the bale chamber and improves the of the plunger mechanism.
Square balers are implements that pick up a swath or windrow of crop material, such as straw or hay, from the ground and deposit it in an infeed housing where it is conveyed by a feed mechanism through an inlet to a bale forming chamber. Four walls define the bale forming chamber where the crop material is urged rearwardly by a reciprocating plunger to form a rectangular package of compacted crop material. Knives positioned on the plunger sever the crop material at the juncture of the bale chamber and the crop inlet as the plunger passes so that the plunger may urge the crop material rearwardly in the bale chamber to form the compressed crop package in the rearward end of the bale forming chamber. The package so formed is automatically tied by a tying mechanism to complete the bale that is then discharged from the chamber by being urged rearwardly by the next bale being successively formed. Completed bales are either deposited on the ground for subsequent retrieval or they are delivered by appropriate means to a trailing wagon hitched to the back of the baler.
The plunger is guided within the bale chamber by rollers and sliding guide (slider) blocks which keep the working surface of the plunger perpendicularly aligned with the walls of the bale chamber. Maintaining plunger alignment is crucial to maintaining knife clearances necessary to assure proper and efficient operation of the square baler. Pressure for increased efficiency in agricultural operations has led to simplified plunger designs. Plunger tail length along the reciprocating axis has been decreased and cam bearings have been replaced with slider blocks formed from wear-resistant materials to simplify the plunger design. Such improvements in production efficiency have not been without consequence. Over time, such simplified designs have proven to lack the desired adjustment longevity and durability needed to satisfy ever-increasing customer demands. Reductions in plunger tail length have resulted in reductions in the durability of the slider blocks with a corresponding adverse affect on the ability to maintain the plunger knife settings.
It would be a great advantage to provide an improved bale plunger guide design which would improve guide control of a reciprocating plunger in a bale chamber and increase the durability of the slider blocks thereby improving the operational performance and service interval in a small square baler thereby overcoming the above problems and disadvantages. Still further advantages would be realized by providing an improved design for the plunger guide that utilizes many of the production efficiencies previously incorporated into the plunger design while improving plunger movement control.